Current Headsets provide wired or wireless connectivity with cellular phones or music players via non custom or semicustom ear canal adaptors that result in poor retention and inconsistent sound level and frequency response. More people wear headsets for longer periods of time and they tend to leave them on even when they are not in use (communicating with external devices, cell-phones, etc). Very few of those devices may have a pass-thru mode, where sounds are passed from the microphone to the speaker/receiver of the headset.
When the physical fit is tight, the headset acts as an earplug, if the pass-thru mode is not available, reducing contact of the user with the environment in addition to being uncomfortable both because of the pressure applied on the ear canal walls as well as the fullness of the occluded canal.
When the fit is loose, the device is not acting as an earplug to the surrounding sounds but it is still uncomfortable since it needs to be continuously readjusted and repositioned. More importantly, because sound enters the ear directly, the signal enhancing processing algorithms such as noise reduction, or directionality are heavily compromised. When the device is used in a pass thru mode, where sound from the microphone is passed to the speaker/receiver of the unit, higher levels of amplification/equalization are not possible due to the loose physical fit (large volume of air) and the echo/feedback cancellation processing is compromised.
The current headsets over-amplify the low frequencies to compensate for the loose fit but cannot adjust the low frequencies to match the variability of the fit. Miniature extended frequency response receivers/speakers suitable for the small volumes of the enclosed ear canal depend on a good tight fit to deliver extended frequency response for a true pass-thru mode especially for non hearing impaired users.
Further yet, the current headset devices do not provide for a way for equalization (other than over all volume) nor for hearing compensation procedures and tools. The receivers/speakers used in current headsets are not suitable for users with hearing impairment because they have extended lower frequencies in addition to over amplifying them and causing masking to upper frequencies where the impairment is usually manifested.